Ultraviolet radiation absorbing polyethers

ABSTRACT

A polymer composition comprising a linear ultraviolet radiation absorbing polyether that comprises a chemically bound UV-chromophore.

This application is a continuation of U.S. application Ser. No.13/799222 filed on Mar. 13, 2013, which claims the benefit of U.S.provisional application 61/665439 filed Jun. 28, 2012, the completedisclosure of which is hereby incorporated herein by reference for allpurposes.

FIELD OF THE INVENTION

The invention relates to polymers bearing a UV-chromophore. Morespecifically, the invention relates to polymer compositions including alinear ultraviolet radiation absorbing polyether that includes achemically bound UV-chromophore.

BACKGROUND OF THE INVENTION

Skin cancer is a significant public health concern which represents 50%of diagnosed cases of cancer in the United States. Ultraviolet radiation(UV) can cause molecular and cellular level damage, and is consideredthe leading environmental factor responsible for skin cancer. Theprolonged exposure to UV radiation, such as from the sun, can lead tothe formation of light dermatoses and erythemas, as well as increase therisk of skin cancers, such as melanoma, and accelerate skin agingprocesses, such as loss of skin elasticity and wrinkling.

The damaging effects of UV exposure can be suppressed by topicalapplication of sunscreens which contain compounds that absorb, reflector scatter UV, typically in the UVA (wavelengths from about 320 to 400nm) or UVB (wavelengths from around 290 to 320 nm) range of thespectrum. Numerous sunscreen compounds are commercially available withvarying ability to shield the body from ultraviolet light.

It has been suggested to use sunscreen molecules having high molecularweights in order to reduce the penetration of the sunscreen moleculethrough the epidermis. However, the inventors have recognized that itwould be desirable to have entirely new polymeric sunscreen compounds(ultraviolet radiation-absorbing polymers) in order to provide any ofvarious benefits such as improved protection from UV.

SUMMARY OF THE INVENTION

The invention includes polymer compositions including a linearultraviolet radiation absorbing polyether that includes a chemicallybound UV-chromophore, and compositions that provide protection fromultraviolet radiation and that include such UV-absorbing polymercompositions.

DETAILED DESCRIPTION OF THE INVENTION

It is believed that one skilled in the art can, based upon thedescription herein, utilize the present invention to its fullest extent.The following specific embodiments are to be construed as merelyillustrative, and not limitative of the remainder of the disclosure inany way whatsoever. Unless defined otherwise, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which the inventionbelongs. With the exception of express references to number averagemolecular weight (M_(n)), all other references to molecular weight areweight average molecular weight (M_(w)). Also, all publications, patentapplications, patents, and other references mentioned herein areincorporated by reference.

UV Absorbing Polymer

Embodiments of the invention relate to polymer compositions including anultraviolet radiation absorbing polyether, (i.e., “UV absorbingpolyether”). By UV absorbing polyether, it is meant a polyether thatabsorbs radiation in some portion of the ultraviolet spectrum(wavelengths between 290 and 400 nm). The UV absorbing polyether has aweight average molecular weight (M_(w)), which may be suitable forreducing or preventing the chromophore from absorbing through the skin.According to one embodiment, a suitable molecular weight for the UVabsorbing polyether is M_(w) greater than 500. In one embodiment, M_(w)is in the range of about 500 to about 50,000. In another embodiment, theM_(w) is in the range of about 1000 to about 20,000, such as from about1000 to about 10,000.

Described herein is a polymer composition including a UV absorbingpolyether. As one skilled in the art will recognize “polyether”indicates that the UV absorbing polymer includes a plurality of etherfunctional groups covalently bonded to each other. The “backbone” of theUV absorbing polyether refers to the longest continuous sequence ofcovalently bonded ether functional groups. Other smaller groups ofcovalently bonded atoms are considered pendant groups that branch fromthe backbone.

According to certain embodiments the polyether includes glyceryl repeatunits and accordingly, may be characterized as a polyglycerol. By“glyceryl repeat units” (also referred to herein “glyceryl remnantunits”) it is meant glycerol units excluding nucleophilic groups such ashydroxyl groups. Glyceryl remnant units include ether functional groups,and generally may be represented as C₃H₅O for linear and dendriticremnants (Rokicki et al. Green Chemistry., 2005, 7, 52). Suitableglyceryl remnant units include dehydrated forms (i.e. one mole of waterremoved) of the following glyceryl units: linear-1,4 (L_(1,4)) glycerylunits; linear-1,3 (L_(1,3)) glyceryl repeat units; dendritic (D)glyceryl units; terminal-1,2 (T_(1,2)) units; and terminal-1,3 (T_(1,3))units. Examples of linear glyceryl remnant units and terminal units areshown below (to the right side of the arrows). The correspondingglyceryl unit before dehydration (shown to the left side of arrows;includes hydroxyls) are shown as well:

-   -   linear-1,4 (L_(1,4)) glyceryl repeat units

linear-1,3 (L_(1,3)) glyceryl repeat units

terminal-1,2 (T_(1,2)) units

and terminal-1,3 (T_(1,3)) units

The polymer composition includes a linear ultraviolet radiationabsorbing polyether that comprises a chemically bound ultravioletradiation-absorbing chromophore (“UV-chromophore”). By linear, it ismeant the UV absorbing polyether has a backbone that is unbranched.

According to certain embodiments, the polymer composition comprisesabout 50% or more of the linear ultraviolet radiation absorbingpolyether that comprises a chemically bound UV-chromophore. According tocertain other embodiments, the polymer composition comprises about 75%or more of the linear ultraviolet radiation absorbing polyether thatcomprises a chemically bound UV-chromophore. According to certain otherembodiments, the polymer composition comprises about 90% or more of thelinear ultraviolet radiation absorbing polyether, such as about 95% ormore. According to certain other embodiments, in addition to the linearultraviolet radiation absorbing polyether, the polymer compositioncomprises a branched ultraviolet radiation absorbing polyether that isnot hyperbranched. In another embodiment, the polymer composition issubstantially free of hyperbranched ultraviolet radiation absorbingpolyethers (e.g., includes less than about 1% by weight of hyperbranchedultraviolet radiation absorbing polyether, such as less than about 0.1%by weight, such as completely free of hyperbranched ultravioletradiation absorbing polyethers.

According to certain embodiments, the linear ultraviolet radiationabsorbing polyether includes either or both of the repeat units shown inFIG. IA and FIG. IIB, below:

In FORMULAS IA and IIB, Y represents a UV-chromophore, as describedbelow.

An illustrative example of a linear ultraviolet radiation absorbingpolyether that comprises a chemically bound UV-chromophore is shown inFORMULA IIIC.

In the structure illustrated in FORMULA IIIC, X is either a terminalfunctional group or part of the polymer backbone; R is a pendant groupattached to the polymer backbone, and X is a terminal group.

X and R may either be the same or different. X and R may beindependently selected from, for example, hydrogen, linear alkyl,alkenyl or alkynyl hydrocarbon chains, linear siloxanes, and the like.In one embodiment the group X represents octadecane. Y represents aUV-chromophore and the groups represented by Y are described below. Theproportion of ether repeat units bearing substituent Y is a real numberexpressed by Equation 1,

$\begin{matrix}\frac{m}{n + m} & {{Equation}\mspace{14mu} 1}\end{matrix}$

where m and n both represent a real number between 0 and 1, and the sumof n and m equals 1. In one embodiment, the number m=1 and n=0 (thepolymer is a homopolymer and includes the repeat unit of FORMULA IA). Inanother embodiment, the number m<1 (the polymer is a copolymer) with Rand Y pendant groups. For copolymers containing both R and Y pendantgroups, the distribution of the pendant R and Y groups along the polymerchain can be modified to obtain optimal polymer properties. In oneembodiment, the polymer is a random copolymer, and the groups R and Yare statistically distributed along the polymer chain. In anotherembodiment, the polymer is a block copolymer, consisting of alternatingsegments of polymer backbone functionalized with a greater proportion ofeither R or Y. In another embodiment, the distribution of the pendantgroups R and Y along the polymer backbone is somewhere between theboundary conditions of block and statistically random copolymers. InFORMULA IIIC, the integers o and p represent the number of CH₂ groups inthe repeat units bearing Y and R.

Introduction of varied R pendant groups can be achieved through the useof other co-monomers during the polymerization reaction. The size,chemical composition, weight percent and position in the backbone ofthese co-monomers can be varied to change the physical and chemicalproperties of the final polymer. Examples of co-monomers that can beincorporated into the polymer include, but are not limited to, ethyleneoxide, propylene oxide, and glycidyl ethers such as n-butyl glycidylether, 2-ethylhexylglycidyl ether.

It is clear to one skilled in the art that polyethers of the typeillustrated in FORMULAS IA, IIB and IIIC can be obtained through varioussynthetic routes; among these routes is ring-opening polymerization ofcyclic ether monomers and optional co-monomers. The size of the ring inthe cyclic ether monomers determines the values of o or p, and theresulting backbone structure of the polyether polymer. For monomers orco-monomers that are epoxides (three-membered rings containing twocarbon atoms and one oxygen atom), the value of o or p in the resultingUV absorbing polyether is 1. A repeat unit that results from using anepoxide co-monomer is shown in structure A of FORMULA IV. For(co)monomers that are oxetanes (four-membered rings containing threecarbon atoms and one oxygen atom), the value of o or p in the resultingUV absorbing polyether is 2. A repeat unit that results from using anoxetane co-monomer is shown in structure B of FORMULA IV. The length ofthe alkyl chain within each monomer type can be selected to modify theproperties of the polymer. In one embodiment, both o and p equal 1. Anexample of this case is if the repeat units bearing Y and R are bothderived from epoxide monomers (o=p=1), or both derived from oxetanemonomers (o=p=2). In another embodiment, o and p are not equal. Anexample of this case is if the repeat units bearing the UV-chromophore Yare based on an epoxide monomer (o=1), and the repeat units bearing thegroup R are based on an oxetane monomer (p=2).

Suitable UV-chromophores that may be chemically bound in UV absorbingpolyethers of the present invention include UV absorbing triazoles (amoiety containing a five-membered heterocyclic ring with two carbon andthree nitrogen atoms), such as benzotriazoles. In another embodiment,the structure represented by Y contains or has a pendant UV absorbingtriazine (a six membered heterocycle containing three nitrogen and threecarbon atoms). Suitable UV-chromophores include those that haveabsorbance of UVA radiation; other suitable UV-chromophores are thosewhich have absorbance in the UVB region. In one embodiment, theUV-chromophore absorbs in both the UVA and UVB region. In oneembodiment, when the UV-absorbing polyether is cast into a film, it ispossible to generate a molar extinction coefficient measured for atleast one wavelength in this wavelength range of at least about 1000mol⁻¹ cm⁻¹, preferably at least about 2000 mol⁻¹ cm⁻¹, more preferablyat least about 4000 mol⁻¹ cm⁻¹. In one embodiment, the molar extinctioncoefficient among at least 40% of the wavelengths in this portion of thespectrum is at least about 1000 mol⁻¹ cm⁻¹. Examples of UV-chromophoresthat are UVA absorbing include triazoles such as benzotriazoles, such ashydroxyphenyl-benzotriazoles; camphors such as benzylidene camphor andits derivatives (such as terephthalylidene dicamphor sulfonic acid);dibenzoylmethanes and their derivatives.

In one embodiment, the UV-chromophore is a benzotriazole providing bothphotostability and strong UVA absorbance with a structure represented inFORMULA V.

wherein each R₁₄ is independently selected from the group consisting ofhydrogen, C₁-C₂₀ alkyl, alkoxy, acyl, alkyloxy, alkylamino, and halogen;R₁₅ is independently selected from the group consisting of hydrogen,C₁-C₂₀ alkyl, alkoxy, acyl, alkyloxy, and alkylamino, R₂₁ is selectedfrom C₁-C₂₀ alkyl, alkoxy, acyl, alkyloxy, and alkylamino. Either of theR₁₅ or R₂₁ groups may include functional groups that allow attachment toa polymer. Compounds resembling the structure in FORMULA V are describedin U.S. Pat. No. 5,869,030, and include, but are not limited to,methylene bis-benzotriazolyl tetramethylbutylphenol (a compound soldunder the trade name TINSORB M by BASF Corporation, Wyandotte, Mich.).In one embodiment, the UV absorbing triazole is derived from atransesterification product of3-(3-(2H-benzo[d][1,2,3]triazol-2-yl)-5-(tert-butyl)-4-hydroxyphenyl)propanoicacid with polyethylene glycol 300, commercially available as TINUVIN213, also available from BASF. In another embodiment, the UV absorbingtriazole is Benzenepropanoic acid,3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-, C₇-₉-branchedand linear alkyl esters, commercially available as TINUVIN 99, alsoavailable from BASF. In another embodiment, the UV absorbing groupcontains a triazine moiety. An exemplary triazine is6-octyl-2-(4-(4,6-di([1,1′-biphenyl]-4-yl)-1,3,5-triazin-2-yl)-3-hydroxyphenoxy)propanoate(a compound sold under the trade name TINUVIN 479 by BASF Corporation,Wyandotte, Mich.).

In another embodiment, the UV-chromophore is a UVB absorbing moiety. ByUVB absorbing chromophore it is meant that the UV-chromophore hasabsorbance in the UVB portion (290 to 320 nm) of the ultravioletspectrum. In one embodiment, the criteria for consideration as a UVBabsorbing chromophore is similar to those described above for an UVAabsorbing chromophore, except that the wavelength range is 290 nm to 320nm. Examples of suitable UVB absorbing chromophores include4-aminobenzoic acid and alkane esters thereof; anthranilic acid andalkane esters thereof; salicylic acid and alkane esters thereof;hydroxycinnamic acid alkane esters thereof; dihydroxy-, dicarboxy-, andhydroxycarboxybenzophenones and alkane ester or acid halide derivativesthereof; dihydroxy-, dicarboxy-, and hydroxycarboxychalcones and alkaneester or acid halide derivatives thereof; dihydroxy-, dicarboxy-, andhydroxycarboxycoumarins and alkane ester or acid halide derivativesthereof; benzalmalonate (benzylidene malonate); benzimidazolederivatives (such as phenyl benzilimazole sulfonic acid, PBSA),benzoxazole derivatives, and other suitably functionalized speciescapable of copolymerization within the polymer chain. In anotherembodiment, the UV-absorbing polyether includes more than oneUV-chromophore or more than one chemical class of UV-chromophore.

UV-absorbing polyethers of the present invention may be synthesized by,according to certain embodiments, ring-opening polymerization of asuitable cyclic ether monomer to form a polyether, followed by covalentattachment of UV-chromophores to pendant functional groups(“post-polymerization attachment”). According to certain otherembodiments, the UV-absorbing polyethers may be synthesized bypolymerization of a cyclic ether monomer, wherein the monomer itselfincludes a covalently attached UV-chromophore (i.e., “directpolymerization”).

Furthermore, as one skilled in the art will recognize, the synthesis ofthe UV absorbing polyether generally results in a reaction product thatis polymer composition that is a mixture of various molecular weights ofUV absorbing polyethers. In certain other embodiments, the reactionproduct may further include (apart from the polymer composition) a smallamount of unpolymerized material which may be removed using techniquesknown in the art.

According to certain embodiments, the polymer composition has a lowpolydispersity. For example, the polydispersity index of the polymercomposition may be about 1.5 or less, such as about 1.2 or less.Polydispersity index is defined as M_(w)/M_(N) (i.e., the ratio ofweight average molecular weight, M_(w) to number average molecularweight, M_(N)). According to certain other embodiments, the polymercomposition includes 50% or more by weight of a particular polymermolecule.

Polydispersity of the polymer composition may be kept low using, forexample, particular synthetic procedures, such as ring-openingpolymerization of a cyclic ether monomer and deprotection (describedbelow). Alternatively or in addition, the polymer composition may betreated using techniques known in the art, such as solvent extractionand or using supercritical CO₂ to purify either the polyether prior topost-polymerization attachment or to purify the final polymercomposition (e.g., after attachment of UV-chromophore).

Synthesis of the polymer by post-polymerization attachment of theUV-chromophore may include the steps of ring-opening polymerization of acyclic ether monomer to form a polyether having protected groups;deprotecting the polyether to remove at least some of the protectedgroups; and attaching a UV-chromophore to the deprotected UV-absorbingpolyether to form a UV-absorbing polyether having a chemically bound UVchromophore.

An example of post-polymerization attachment is illustratedschematically in FORMULA VI. An initiator I is used to inducepolymerization of cyclic ether monomer M, generating polymer P₀ whereinpendant hydroxy functional groups are protected with a protecting group(P). Polymer P₀ is subjected to conditions that remove protecting groupP, affording deprotected polymer P_(d). Finally, UV-chromophore Y isattached to the pendant hydroxyl groups of polymer P_(d), affording thedesired final polymer, P_(f).

Ring-opening polymerization of cyclic ethers such as monomer M inFORMULA VI can be achieved using various methods including cationic andanionic ring-opening polymerization. In one embodiment, thepolymerization is performed by anionic ring opening polymerization.Monomer M in FORMULA VI is a form of glycidol wherein the primaryhydroxy group has been masked with protecting group P. Polymerization ofunprotected glycidol results in the formation of highly branchedpolymers (U.S. Pat. No. 7,988,953B2, Tokar, R. et. al. Macromolecules1994, 27, 320-322: Sunder, A. et. al. Macromolecules 1999: 4240-4246.Rokicki, G. et. al. Green Chemistry 2005, 7, 529). Conversely, anionicpolymerization of glycidol derivaties where the primary hydroxyl grouphas been protected can generate linear polyethers, as illustrated bystructure P₀ in FORMULA VI (Taton, D. et. al. Macromolecular Chemistryand Physics 1994, 195, 139-148: Erberich, M. et. al. Macromolecules2007, 40, 3070-3079: Haouet, A. et. al. European Polymer Journal 1983,19, 1089-1098: Obermeier, B. et. al Bioconjugate Chemistry 2011, 22,436-444: Lee, B. F. et. al. Journal of polymer science. Part A, Polymerchemistry 2011, 49, 4498-4504). The protected cyclic ether monomer isnot limited to epoxide derivates, and includes functionalized cyclicethers containing 3 through 6 contiguous atoms; in another embodiment,the monomer M is an oxetane derivative containing a protected primaryhydroxyl group.

By protected, it is meant that a functional group in a multifunctionalmolecule has been selectively derivatized with a moiety that preventscovalent modification at that functional group. Moieties that are usedas protecting groups are typically attached to the desired functionalgroups with excellent chemical yield, and can be selectively removed asrequired in good yield, revealing the original functional group.Hydroxyl protecting groups include but are not limited to ethers such asmethyl, methoxylmethyl (MOM), methylthiomethyl (MTM), t-butylthiomethyl,(phenyldimethylsilyl)methoxymethyl (SMOM), benzyloxymethyl (BOM),p-methoxybenzyloxymethyl (PMBM), (4-methoxyphenoxy)methyl (p-AOM),t-butoxymethyl, 4-pentenyloxymethyl (POM), siloxymethyl,2-methoxyethoxymethyl (MEM), 2,2,2-trichloroethoxymethyl,bis(2-chloroethoxy)methyl, 2-(trimethylsilyl)ethoxymethyl (SEMOR),tetrahydropyranyl (THP), allyl, 3-bromotetrahydropyranyl,tetrahydrothiopyranyl, 1-methoxycyclohexyl, benzyloxy-2-fluoroethyl,2,2,2-trichloroethyl, 2-trimethylsilylethyl, 2-(phenylselenyl)ethyl,t-butyl, allyl, p-chlorophenyl, p-methoxyphenyl, 2,4-dinitrophenyl,benzyl, p-methoxybenzyl, 3,4-dimethoxybenzyl, o-nitrobenzyl,p-nitrobenzyl, p-halobenzyl, 2,6-dichlorobenzyl, trimethylsilyl (TMS),triethylsilyl (TES), trii sopropylsilyl (TIPS), t-butyldimethylsilyl(TBDMS), t-butyldiphenylsilyl (TBDPS), tribenzylsilyl, esters such asformate, benzoylformate, acetate, chloroacetate, dichloroacetate,trichloroacetate, trifluoroacetate, methoxyacetate,triphenylmethoxyacetate, phenoxyacetate, p-chlorophenoxyacetate,3-phenylpropionate, 4-oxopentanoate (levulinate),4,4-(ethylenedithio)pentanoate (levulinoyldithioacetal), pivaloate,adamantoate, crotonate, 4-methoxycrotonate, benzoate, p-phenylbenzoate,2,4,6-trimethylbenzoate (mesitoate), and carbonates such as alkyl methylcarbonate, 9-fluorenylmethyl carbonate (Fmoc), alkyl ethyl carbonate,alkyl 2,2,2-trichloroethyl carbonate (Troc), 2-(trimethylsilyl)ethylcarbonate (TMSEC), 2-(phenylsulfonyl)ethyl carbonate (Psec),2-(triphenylphosphonio) ethyl carbonate (Peoc), alkyl isobutylcarbonate. In one embodiment, the protecting group is ethoxyethyl ether;in another embodiment, the protecting group is allyl ether.

Removal of protecting groups from the protected linear polyether P₀ togenerate deprotected polymer P_(d) is achieved using methodscomplimentary to the choice of protecting group P; such methods arefamiliar to those skilled in the art. In one embodiment, the primaryhydroxyl group of the cyclic ether monomer is protected as the1-ethoxyethyl ether; the cleavage of this protecting group to generatethe deprotected polymer is achieved using aqueous acidic conditions suchas aqueous acetic acid, aqueous hydrochloric acid, or acidic ionexchange resin. In another embodiment, the primary hydroxyl group of thecyclic ether monomer protected as an allyl ether; the cleavage of thisprotecting group to generate the deprotected polymer is achieved byisomerizaion of the allyl ether to the vinyl ether by treatment withpotassium alkoxide followed by treatment with aqueous acid,isomerization using transition metal catalysts followed by acidichydrolysis, or direct removal using palladium (0) catalysts and anucleophilic scavenger.

The anionic ring-opening polymerization of monomer M illustrated inFORMULA VI is initiated by alkoxide salt I. Examples of alkoxidessuitable for initiation of ring-opening polymerization of cyclic ethermonomers include, but are not limited to the potassium salts of linearC3 through C30 hydrocarbon alcohols, polyethylene glycol methyl ether,and carbinol terminated polysiloxanes. In one embodiment, the initiatorfor anionic ring-opening polymerization is the potassium salt ofoctadecanol. Another embodiment of the current invention makes use of amultifunctional initiator including, but not limited to polyoxyalkylenessuch as polyethylene glycol, polypropylene glycol or poly(tetramethyleneether) glycol; polyesters such as poly(ethyleneadipate),poly(ethylenesuccinate); copolymers that have both oxyalkylene and esterfunctionality in the backbone such as poly[di(ethylene glycol)adipate];and lower molecular weight alcohols such as 1,4-butanediol,1,6-hexanediol or neopentyl glycol.

Depending on the functional groups pendant from the polymer,chromophores can be covalently attached to the polymer backbone using avariety of methods known to those skilled in the art. The followingmethods are illustrative, and do not represent an exhaustive list of thepossible means to attach a UV-chromophore to the polymer backbone. Inthe case of polymers with free hydroxyl groups (as represented bystructure P_(d) FORMULA VI) a UV-chromophore containing a carboxylategroup may be covalently attached to the polymer using a number ofmethods familiar to those skilled in the art. Condensation reagents canbe used to form covalent bonds between UV-chromophores with carboxylicacids and hydroxyl groups on polymers generating ester bonds; in oneembodiment, the condensation reagent isN-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride. Thecarboxylic acid of the UV-chromophore may also be attached to hydroxylgroups on the polymer through ester bonds using transition metalcatalysis; in one embodiment, the catalyst is tin (II) ethylhexanoate.The UV-chromophore can also be attached to the polymer by converting thecarboxylic acid of the UV-chromophore to the corresponding acidchloride; the acid chloride reacts with hydroxyl groups on thefunctional polymer forming ester bonds; in one embodiment, thisconversion to the acid chloride is performed using thionyl chloride. TheUV-chromophore carboxylic acid may also be converted to the isocyanatethrough Curtius rearrangement of an intermediate acid azide; thechromophore isocyanate reacts with hydroxyl groups on the functionalpolymer forming a urethane bonds. In another embodiment, the carboxylicacid on the UV-chromophore can be converted to an ester, and attached tothe hydroxyl group on the backbone by transesterification. This can beachieved by conversion of the carboxylic acid to an ester with a lowboiling alcohol such as methanol; transesterification is performed byreacting the chromophore ester with the polymer containing side chainhydroxyl groups using an acid catalyst, for instance, para-toluenesulfonic acid.

In the case of polymers with free hydroxyl groups (as represented bystructure P_(d) in FORMULA VI) a UV-chromophore containing a hydroxylgroup may be covalently attached to the polymer using a number ofmethods familiar to those skilled in the art. In one embodiment, thehydroxyl group on the UV-chromophore can be activated for nucleophilicdisplacement using a reagent such as methane sulfonyl chloride orp-toluene sulfonyl chloride; the hydroxyl groups on the backbone arethen able to displace the resulting mesylate or tosylate under basicconditions to generate an ether bond between the polymer and theUV-chromophore. In another embodiment, the hydroxyl group on theUV-chromophore can be converted to the chloroformate using a reagentsuch as phosgene, diphosgene, or triphosgene; the resultingUV-chromophore chloroformate can react with hydroxyl groups on thebackbone of the polymer to generate a carbonate bond between the polymerand the UV-chromophore.

In the case of polymers with free hydroxyl groups (as represented bystructure P_(d) in FORMULA VI) a UV-chromophore containing an aminegroup may be covalently attached to the polymer using a number ofmethods familiar to those skilled in the art. In one embodiment, thehydroxyl groups on the polymer can be converted to the correspondingchloroformates using a reagent such as phosgene, diphosgene andtriphosgene; the amine functionalized UV-chromophore can then react withthe polymer chloroformates generating a carbamate bond between theUV-chromophore and polymer.

In another embodiment, some of the hydroxyl groups on the linear polymerbackbone remain after the acid, acid chloride or isocyanate functionalUV-chromophores are attached. These unreacted hydroxyl groups may beused to attach other monofunctional side groups to improve the physicaland chemical properties of the polymer. Examples of hydroxyl reactivefunctional groups include, but are not limited to, acid chlorides andisocyanates. Specific examples of hydroxyl reactive functional sidegroups include palmitoyl chloride and stearyl isocyanate. Other examplesof groups that may be pendant from polymers that are sites for covalentattachment of UV-chromophores include, but are not limited to,conjugated alkenes, amines, and carboxylic acids.

In a another embodiment, the polyether backbone is a polyglycerol withpendant hydroxyl groups or hydrophobic groups, such as a polyglycerylester, for example, decaglyceryl monostearate sold under the tradenamePOLYALDO 10-1-S by Lonza in Allendale, N.J. or tetradecaglycerylmonostearate sold under the tradename POLYALDO 14-1-S by Lonza inAllendale, N.J. The pendant hydroxyl groups may be reacted with aUV-chromophore containing a complementary functional group as describedabove to obtain a UV absorbing polyether. In this embodiment, thepolymer composition will be, for example, the reaction product of apolyglycerol ester and a UV chromophore having a functional groupsuitable for covalent attachment to said polyglycerol ester. Suitablefunctional groups on the UV chromophore include carboxylates,isocyanates, among other functional groups discussed previously. Theresulting polymer composition may include a linear UV-absorbingpolyether having the repeat unit shown in FORMULA IIB. The resultingpolymer composition may further include some non-linear (e.g., cycliccomponents) as well, depending upon the percentage of linear materialpresent in the polyglycerol.

As described above, the synthesis of functionalized polymers, such asthose in FORMULA IIIC, could also be achieved through polymerization ofUV-chromophores covalently modified with cyclic ether groups (directpolymerization). This is illustrated in FORMULA VII, where Y representsa UV-chromophore, and o is a characteristic of the ring size of thecyclic ether monomer.

As one skilled in the art will recognize the reaction product to makethe UV-absorbing polyether may include not only the polymer composition,but may also include some unreacted/unpolymerized.

The UV absorbing polymers described herein are useful in applicationswhere UV absorption is desired. For example, the polymer may be usefulfor combining with a suitable cosmetically acceptable carrier forcosmetic applications or combining the UV absorbing polymer with othermaterials to reduce UV degradation of the materials (i.e., melt blendingthe material with the UV absorbing polymer or coating the material withthe UV absorbing polymer). The incorporation of polymers of the presentinvention into such compositions may provide enhanced SPF (primarily UVBabsorbance), enhanced PFA (primarily UVA absorbance) or enhancement ofboth. The cosmetically-acceptable topical carrier is suitable fortopical application to human skin and may include for example, one ormore of vehicles such as water, ethanol, isopropanol, emollients,humectants, and/or one or more of surfactants/emulsifiers, fragrances,preservatives, water-proofing polymers, and similar ingredients commonlyused in cosmetic formulations. As such, the UV absorbing polymer may beformulated using ingredients known in the art into a spray, lotion, gel,stick or other product forms. Similarly, according to certainembodiments, one may protect human skin from UV radiation by topicallyapplying a composition comprising the UV absorbing polymer.

The following examples are illustrative of the principles and practiceof this invention, although not limited thereto. Numerous additionalembodiments within the scope and spirit of the invention will becomeapparent to those skilled in the art once having the benefit of thisdisclosure.

EXAMPLES Example 1 Synthesis of a Protected Form of glycidol

The synthesis of protected epoxide monomer 1 was performed asillustrated in FORMULA VIII using a variation of a procedure describedin the literature (Fitton, A. et. al. Synthesis 1987, 1987, 1140-1142).Glycidol (53 mL, 0.80 moles) and ethyl vinyl ether (230 mL, 2.40 moles;distilled immediately before reaction) were added to a 2-neck 500 mLround bottom flask containing a magnetic stir bar. The flask was fittedwith a septum and thermometer adapter; a thermometer was inserted intothe adapter and positioned such that the bulb was immersed in theliquid. The flask was immersed in a brine/ice bath; the mixture wasmagnetically stirred. When the internal temperature was 0° C., p-toluenesulfonic acid hydrate (pTSA.H₂O, 1.43 g, 7.5 mmol) was added in smallportions while stirring vigorously. On addition of each portion of pTSA,the temperature of the solution increased sharply; the rate of additionwas slow enough to prevent the solution temperature increasing above 20°C. The final portion of pTSA was added ˜5 hours after addition of theinitial portion, and resulted in no exotherm; thin layer chromatographyof the reaction mixture revealed no residual glycidol following thefinal pTSA addition. The reaction mixture was transferred into aseparatory funnel; saturated aqueous NaHCO₃ (230 mL) was poured into thefunnel slowly. The mixture was shaken, the layers allowed to separate,and the organic layer was removed, dried over sodium sulfate, andfiltered through paper. The solution was concentrated by rotaryevaporation, then vacuum distilled (60° C. distillate at 8 torr)affording protected epoxide monomer 1 (79.38 g) as a clear oil. NMRanalysis was performed on a Varian Unity Inova 400 MHz spectrometer (¹H)spectrometer at 30° C.; chemical shifts are reported in parts permillion (ppm) on the δ scale, and were referenced to residual protonatedsolvent peaks or tetramethylsilane. Spectra obtained in DMSO-d₆ werereferenced to (CHD₂)(CD₃)SO at δ_(H) 2.50. ¹H NMR (400 MHz, CDCl₃) δ ppm4.76 (quin, J=5.2 Hz, 1H), 3.81 (dd, J=11.5, 3.3 Hz, 1H), 3.60-3.74 (m,3H), 3.38-3.60 (m, 4H), 3.10-3.20 (m, 2H), 2.81 (ddd, J=5.1, 4.0, 1.3Hz, 2H), 2.63 (ddd, J=14.6, 5.1, 2.7 Hz, 2H), 1.33 (dd, 5.4 Hz, 6H),1.21 (td, J=7.1, 1.3 Hz, 6H).

Example 2A Synthesis of Linear polyglycerol

Polymerization of protected epoxide monomer 1 was achieved asillustrated in FORMULA IX. 1-Octadecanol (27.76 g, 102.6 mmol) was addedto an oven-dried 250 mL 2-neck round bottom flask containing a magneticstir bar. The flask was fitted with a nitrogen inlet adapter and rubberseptum. Potassium methoxide (25 wt % in methanol (MeOH), 6.06 mL, 20.52mmol) was added to the flask by syringe through the septum. The roundbottom flask was immersed in an oil bath which had been pre-heated to90° C. The septum was pierced with an 18 gauge needle, and the materialin the flask was stirred under a constant stream of nitrogen gas for 1hour, during which time the alcohol melted, and methanol evaporated fromthe flask. The septum was replaced with a pressure equalizing additionfunnel containing monomer 1 (151 g, 1.04 moles). The funnel was sealedwith a rubber septum. The monomer 1 was added dropwise to the stirredmixture; the reaction mixture was stirred at 90° C. for 15 hours. Oncooling, this afforded crude polyether 2 as a pale brown, slightlyviscous oil that was used in subsequent reactions without furtherpurification. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 4.48-4.80 (m, 10H),3.25-3.97 (m, 70H), 1.41-1.64 (m, 2H), 1.23-1.40 (m, 60H), 1.09-1.23 (m,30H), 0.88 (t, J=7.0 Hz, 3H).

Gel permeation chromatography for molecular weight determination wasperformed at 35° C. on a Waters Alliance 2695 Separations Module(Waters, Milford, Mass.) at a flow rate of 0.5 mL/min THF (stabilizedw/0.025% BHT). The 2695 was equipped with two GPC columns in series(Waters Corp HR 0.5 and HR3) with dimensions of 7.8×300 mm with 5 μmparticle size) and a Waters model 410 refractive index detector. Themolecular weights of the samples were determined by comparison topolystyrene standards. Standards were prepared by weighing 1-2 mg ofeach polystyrene (PS) polymer into a 2 mL vial with THF solvent (2standards per vial); samples were filtered (0.22 μm) prior to analysis.Polystyrene standards spanned a range between 70,000 to 600 Daltons, andwere manufactured by three vendors (Polymer Standards Service-USA,Phenomenex and Shodex). The resultant calibration curve provided anr²=0.9999. Experimental samples were dissolved in THF at a concentrationof 3-5 mg/mL and filtered (0.22 μm) prior to analysis. GPC (THF)analysis for polymer 2: M_(w) 1724.

Crude polyether 2 was transferred with tetrahydrofuran (THF, ˜500 mL)into a 1 L round bottom flask containing a magnetic stir bar.Concentrated aqueous HCl (37%, 20 mL) was added to the stirred reactionmixture by glass pipette. After 16 hours, the reaction mixture wasconcentrated by rotary evaporation to an oil which was diluted withmethanol to ˜500 mL. Solid NaHCO₃ was added in portions to thevigorously stirred solution, causing significant bubbling. When additionof the NaHCO₃ did not produce further bubbling (total NaHCO₃ added was107 g) the mixture was filtered through paper to remove solid NaHCO₃.The filtrate was concentrated by rotary evaporation affording linearpolyglycerol 3 as a tan foam. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 4.43 (br.s., 11H), 3.20-3.70 (m, 52H), 1.38-1.55 (m, 2H), 1.23 (s, 30H), 0.85 (t,J=7.0 Hz, 3H).

Example 2B Synthesis of Linear polyglycerol

A different batch of protected crude polymer 2 (260 g) and methanol (ACSgrade, 1.25 L) was transferred into a 2 L 2-neck round bottom flask.Dry, H⁺ form acidic ion-exchange resin in (Dowex DR-2030 from Aldrich,446483; 100.3 g) was added to the flask. The center neck of the flaskwas fitted with an adapter for mechanical stirring and a paddle; theside neck of the flask was fitted with a water cooled distillationadapter. The reaction flask was immersed in an oil bath. With vigorousmechanical stirring, the reaction mixture was heated to boiling (oilbath temperature of 85° C.). Methanol (and the methyl ether resultingfrom removal of the protecting groups) was distilled from the flask.After 750 mL of methanol were collected, an additional portion ofmethanol (750 mL) was added to the reaction mixture. Another 750 mL ofmethanol was allowed to distill from the flask. Decolorizing charcoalwas added to the hot reaction mixture. The mixture was stirred brieflyand then filtered through paper. The filtrate was concentrated by rotaryevaporation. Residual solvent was removed under vacuum affording thefinal linear polyglycerol as a yellowish foam (107 g).

Example 3A Synthesis of benzotriazole chromophore carboxylate

The polyethylene glycol ester of3-[3-(2H-1,2,3-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propanoate(a chromophore sold under the trade name TINUVIN 213 by BASFCorporation, Wyandotte, Mich.) (81.0 g) was added to a 2 L round bottomflask containing a magnetic stir bar. EtOH (600 mL) was added to theflask by funnel, and the mixture was stirred until homogeneous. Sodiumhydroxide (NaOH, 30.8 g) was dissolved in H₂O (400 mL); the basicsolution was transferred into an addition funnel above the 2 L flask.The NaOH solution was added slowly to the stirred mixture; the paleamber cloudy solution immediately turned clear and dark orange. Whenaddition was complete, the mixture was stirred overnight at roomtemperature. The solution was concentrated by rotary evaporation toremove most of the EtOH. The resulting orange oil was diluted to 1400 mLwith H₂O. The mixture was stirred mechanically and was acidified to ˜pH1 by addition of 1 M aq. HCl (˜700 mL). The resulting white precipitatewas filtered and pressed to remove water, then recrystallized from EtOH.The first crop of crystals were long, thin colorless needles. Thesupernatant was removed and concentrated by rotary evaporation; a secondcrop of material was isolated as a white, amorphous solid. The two cropswere combined and dried in a vacuum oven overnight affording aUV-chromophore having a carboxylate group, specifically benzotriazolecarboxylate 4,3-(3-(2H-benzo[d][1,2,3]triazol-2-yl)-5-(tert-butyl)-4-hydroxyphenyl)propanoic acid (37.2 g) as a white solid; the structure is illustratedin FORMULA X. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 11.25 (br. s, 1H),8.00-8.20 (m, 2H), 7.95 (d, J=2.1 Hz, 1H), 7.50-7.67 (m, 2H), 7.28 (d,J=2.1 Hz, 1H), 2.87 (t, J=7.5 Hz, 2H), 2.56 (t, J =7.5 Hz, 2H), 1.45 (s,9H).

Example 3B Synthesis of benzotriazole chromophore carboxylate

Benzenepropanoic acid,3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-, C7-9-branchedand linear alkyl esters, commercially available as TINUVIN 99 from BASF(120 g, 265.7 mmol) was added to a 3 L single neck round bottom flaskcontaining a magnetic stir bar. Isopropanol (900 ml, ACS grade) wasadded to the flask, and the resulting mixture was stirred until completedissolution. Sodium hydroxide (36 g, 900 mmol) was dissolved in 600 mlof distilled water, and the solution was added to the reaction mixture.The resulting opaque mixture, which in 40 min became a clear orangesolution, was stirred at room temperature for 24 hours, and then slowlyadded to a vigorously stirred mixture of isopropanol (1800 ml, ACSgrade) and 1N HCl (1200 ml), cooled to 10-15° C. The precipitated whitesolid was filtered, washed with 1.2 L of 1:1 isopropanol-1N HCl mixture,suspended in 2 L of 0.25N HCl, stirred for 1 hour, filtered and dried at90° C. in a vacuum oven overnight. The resulting UV-chromophore having acarboxylate group, specifically a benzotriazole carboxylate 4 (37.2 g)was obtained as a pale yellow solid, 85 g, 94.5%.

Example 4 Esterification of polyether Backbone with benzotriazolecarboxylate

FORMULA XI illustrates the esterification of polyglycerol 3 withbenzotriazole carboxylate 4 using catalytic tin. Linear polyglycerol 3of Example 2A (5.52 g, 60.1 hydroxyl milliequivalents) was dissolved inmethanol and transferred into a 500 mL 2-neck round bottom flask. Themethanol was removed using rotary evaporation; benzotriazole carboxylate4 (20.38 g, 60.1 mmol)) and a magnetic stir bar were added to the flask.The flask was fitted with a nitrogen inlet adapter and vacuumdistillation adapter with 100 mL receiving flask. The flask was placedunder vacuum (<1 Torr) for 1 hour, then backfilled with nitrogen gas.The inlet adapter was removed from the 500 mL flask; tin (II) ethylhexanoate (49 μL, 0.15 mmol) was added to the flask by syringe under astream of nitrogen. The apparatus was reassembled and immersed in an oilbath pre-heated to 200° C. When most of the solid had melted, the oilbath was cooled to 190° C. The reaction was stirred under a flow ofnitrogen for 16 hours. While maintaining temperature and stirring, thereaction flask was then placed under vacuum (<1 Torr) for an additional24 hours. The apparatus was then backfilled with nitrogen and cooled toroom temperature. The material was freeze fractured and ground to powderusing a mortar and pestle. The powder was dissolved in a minimal amountof THF. Methanol (900 mL) and a magnetic stir bar were added to anErlenmeyer flask; the flask was immersed in an ice bath. The THFsolution was added to the methanol with vigorous stirring; the resultingprecipitate was isolated by vacuum filtration. Residual solvent wasremoved under vacuum overnight, affording the linear polyglycerol 5(18.7 g) as an off-white solid. ¹H NMR (400 MHz, CDCl₃) δ ppm 11.71 (br.s., 9H), 8.03 (br. s., 9H), 7.80 (br. s, 18H), 7.28-7.48 (m, 18H), 7.12(br. s, 9H), 5.19 (br. s, 1H), 3.98-4.46 (br. m, 20H), 3.21-3.61 (br. m,32H), 2.91 (br. s, 18H), 2.67 (br. s, 18H), 1.38-1.51 (m, 85H),1.13-1.35 (m, 28H), 0.87 (t, J=6.6 Hz, 3H). GPC (THF): M_(w) 3299; M_(n)2913.

Example 5 Conversion of benzotriazole arboxylate to acid chloride(3-(3-(2H-benzo[d] [1,2,3]triazol-2-yl)-5-(tert-butyl)-4-hydroxyphenyl)propanoyl chloride)

The conversion of the benzotriazole carboxylic acid 4 to thecorresponding benzotriazole acid chloride 6 is illustrated in FORMULAXII. Benzotriazole carboxylate 4 (50 g 147 mmol, synthesized asdescribed in Example 3 was added to a 1000 mL 3-neck flask containing amagnetic stir bar; the flask was equipped with a reflux condenser,nitrogen inlet, and rubber septum. Anhydrous toluene (˜500 mL) wastransferred into the flask by cannula through the septum. Thionylchloride (16.1 mL, 221 mmol) was transferred into the flask by syringe;dimethylformamide (2.7 mL) was then added to the flask by syringe. Theflask was immersed in an oil bath set at 80° C.; the suspension wasstirred; the solids began to disperse, eventually yielding a clearsolution. After ˜4 hours, the reaction mixture was allowed to cool,transferred to a round bottom flask and concentrated by rotaryevaporation. The resulting oil was triturated with hexanes, affording abeige solid. The suspension of material was recrystallized by addingadditional hexanes and warming to reflux, filtration through paper, andslow cooling to room temperature with stirring. The resulting beigecrystals were filtered and dried under vacuum at 50° C. The filtrate wasconcentrated, and the recrystallization performed a second timeaffording a second crop of crystals; the mass of the combined crops ofbenzotriazole acid chloride 6 was 44.7 grams. ¹H NMR (400 MHz, CDCl₃) δ11.88 (s, 1H), 8.16 (d, J=2.2 Hz, 1H), 7.91-7.98 (m, 2H), 7.47-7.54 (m,2H), 7.21 (d, J=2.2 Hz, 1H), 3.29 (t, J =7.5 Hz, 2H), 3.07 (t, J=7.5 Hz,2H), 1.50-1.53 (s, 9H).

Example 6 Conversion of benzotriazole acid chloride to isocyanate(2-(2H-benzo[d][1,2,3]triazol-2-yl)-6-(tert-butyl)-4-(2-isocyanatoethyl)phenol)

Synthesis of a benzotriazole isocyanate 7 suitable for coupling topendant functional groups is illustrated in FORMULA XIII Sodium azide(NaN₃, 2.5 g, 38 mmol: CAUTION! NaN₃ is a violent poison) was carefullytransferred into a single necked 500 mL round bottom flask containing amagnetic stir bar. Deionized water (20 mL) was added to the flask; theNaN₃ dissolved with mixing affording a clear solution. The flask wasimmersed in an ice bath. Acid chloride 6 (7.0 g 20 mmol) and anhydrousacetone (45 mL) were transferred into a pressure equalizing additionfunnel in a positive pressure N₂ atmosphere glove box. The acid chloridedissolved in the acetone with gentle swirling, affording a clear yellowsolution. The addition funnel containing benzotriazole acid chloride 6was fitted into the flask containing the aqueous solution of NaN₃; thetop of the addition funnel was fitted with a N₂ adapter connected to avacuum gas manifold. The solution of benzotriazole acid chloride 6 wasadded dropwise to the NaN₃ solution. After addition of several drops, awhite precipitate began to appear, suspended in the aqueous solution.Addition of benzotriazole acid chloride 6 was complete within 30minutes; mixing was continued for 20 minutes in the ice bath. Water (30mL) was added to the resulting white slurry; solids were collected byfiltration through a glass fritted funnel under vacuum. The white solidwas transferred to a separatory funnel followed with CHCl₃ (185 mL). Theflask was shaken and the layers were allowed to separate. The lowerorganic phase was removed from the small aqueous layer and dried overNa₂SO₄. The solution was filtered; the filtrate was placed in a singlenecked 500 mL round bottom flask containing a magnetic stir bar; theflask was fitted with a reflux condenser with nitrogen inlet adapter andimmersed in an oil bath. The solution was heated slowly to reflux over30 minutes. The final oil bath temperature was 65° C. As the oil bathtemperature surpassed 55° C., bubbling was apparent in the solution. Thereaction was allowed to reflux for a total of 90 min. CHCl₃ was thenremoved by rotary evaporation; the resulting oil crystallized overnighton standing affording the benzotriazole isocyanate 7 (5.8 g) as aslightly grey solid. ¹H NMR (400 MHz, CDCl₃) δ 11.91 (s, 1H), 8.18 (d,J=1.9 Hz, 1H), 7.92-7.98 (m, 2H), 7.47-7.53 (m, 2H), 7.23 (d, J=2.1 Hz,1H), 3.59 (t, J=6.9 Hz, 2H), 2.96 (t, J=6.9 Hz, 2H), 1.52 (s, 9H).

Example 7 Coupling of isocyanate to polyglycerol

The reaction of linear polyglycerol 3 with benzotriazole isocyanate 7 isillustrated in FORMULA XIV. A solution of polyglycerol 3 in methanol wasconcentrated by rotary evaporation; residual solvent was removed in avacuum oven overnight at 75° C. The polymer (2.22 g, 24.1 hydroxylmilliequivalents) was added to a 100 mL 2-neck round bottom flaskcontaining a magnetic stir bar. Isocyanate 7 (7.65 g, 22.7 mmol),bismuth catalyst (25 mg; a bismuth carboxylate complex sold under thetrade name BICAT 8210 by Shepherd Chemical, Norwood, Ohio) and THF (17.4ml, dried over 3 angstrom molecular sieves) were added to the flask. Theflask was placed in a 65° C. heated oil bath and fitted with a gasinlet. The reaction mixture was stirred for 5 hours under a nitrogenatmosphere, then allowed to cool to room temperature. FTIR was used toconfirm the disappearance of the strong isocyanate peak at 2250 cm⁻¹.The reaction mixture was poured into 160 ml of methanol, resulting in atan precipitate. Methanol was decanted off and the product was washed inthe flask with methanol (2×75 mL). Residual solvent was removed in avacuum oven overnight at 60° C.; the material was ground to a finepowder.

Example 8 Synthesis of an epoxide chromophore for the DirectPolymerization Method

The synthesis of an epoxide monomer 9 bearing a benzotriazolechromophore is illustrated in FORMULA XV. A solution of lithium aluminumhydride (LAH) in THF (a 1 M, 250 mL) was transferred by cannula undernitrogen atmosphere into an oven-dried 500 mL 2-neck round bottom flaskcontaining a magnetic stir bar and fitted with a rubber septum andpressure equalizing addition funnel. The reaction flask was immersed inan ice bath; stirring was started. Benzenepropanoic acid,3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy,C7-C9 branchedand linear alkyl ester containing 5 wt. % 1-methoxy-2-propyl acetate(50.06 g; a benzotriazole UV absorbing product sold under the trade nameTINUVIN 99-2 by BASF Corporation, Wyandotte, Mich.) was transferred intothe addition funnel, and dissolved in anhydrous THF (30 mL). The THFsolution containing the benzotriazole was added dropwise to the solutioncontaining LAH; this resulted in slow fizzing. After the addition wascomplete, an additional portion of LAH solution (100 mL) was cannulatedinto the reaction flask. The reaction was allowed to warm to roomtemperature with stirring. After 2 hours, the reaction mixture waspoured into a 1 liter erlenmeyer flask which was immersed in an icebath. The solution was stirred mechanically while water (˜60 mL) wasadded slowly to quench any residual LAH (EXTREME CAUTION: quenching ofLAH with water is exothermic and releases large quantities of highlyflammable H₂ gas). When the LAH was quenched (no additional gas releasedwith additional water), the grey suspension was diluted to 1 L with 1 Maqueous HCl. This solution was transferred into a 2 L separatory funneland extracted with ethyl acetate (1×400 mL, then 2×50 mL). The combinedethyl acetate layers were washed with brine (1×400 mL), dried overNa₂SO₄, then filtered through paper. Solvent was removed first by rotaryevaporation and then in a vacuum oven overnight affording benzotriazolalcohol 8 (42.16 g) as a beige solid with a strong unpleasant odor. ¹HNMR (400 MHz, CDCl₃) δ ppm 11.75 (s, 1H), 8.15 (d, J=2.1 Hz, 1H),7.88-7.99 (m, 2H), 7.43-7.52 (m, 2H), 7.22 (d, J=2.1 Hz, 1H), 3.75 (m,2H), 3.62 (br. s, 1H), 2.77 (t, J=7.7 Hz, 2H), 1.91-2.06 (m, 2H), 1.52(s, 9H).

Sodium hydride (6.0 g, 250 mmol) was added to an oven-dried 3-neck roundbottom flask containing a magnetic stirring bar. The flask was fittedwith a pressure equalizing addition funnel, nitrogen inlet adapter andrubber septum. Anhydrous THF (300 mL) was added to the flask by cannulaunder nitrogen; the flask was then immersed in an ice bath, and stirringwas starting. Benzotriazol Alcohol 8 (20.0 g, 61.5 mmol) and a smallmagnetic stirring bar were added to the addition funnel; THF wascannulated into the addition funnel, and the stir bar was agitated topromote dissolution of the alcohol in the THF. The final volume of thealcohol/THF solution was 65 mL. This solution was added dropwise to thecold, stirred sodium hydride suspension. The cold reaction mixture wasstirred for 1 hour, then epichlorohydrin (20 mL, 256 mmol) was added bysyringe through the septum. The addition funnel was exchanged with areflux condenser with nitrogen inlet, and the round bottom flask wasimmersed in an oil bath at 70° C. The mixture was stirred for 19 hours,then the mixture was transferred to a separatory funnel with 1M aqueousHCl (750 mL) and ethyl acetate (500 mL). After shaking, the aqueouslayer was discarded. The organic layer was washed with water (2×250 mL)and brine (1×250 mL) then dried over Na₂SO₄. The solution wasconcentrated by rotary evaporation. The crude product was purified bychromatography on silica gel (6:1 hexanes/ethyl acetate). Fractionscontaining the desired product were pooled, concentrated by rotaryevaporation; residual solvent was removed under vacuum overnightaffording the epoxide monomer 9 bearing a benzotriazole chromophore(7.35 g) as a beige solid . ¹H NMR (400 MHz, CDCl₃) δ ppm 11.77 (s, 1H),8.14 (d, J=1.9 Hz, 1H), 7.85-8.00 (m, 2H), 7.41-7.53 (m, 2H), 7.21 (d,J=1.9 Hz, 1H), 3.74 (dd, J=11.5, 3.1 Hz, 1H), 3.57 (ddt, J=19.8, 9.3,6.4 Hz, 2H), 3.43 (dd, J=11.5, 5.8 Hz, 1H), 3.19 (ddt, J=5.8, 4.0, 2.9Hz, 1H), 2.82 (br. t, J=4.7 Hz, 1H), 2.76 (br. t, J=7.7 Hz, 2H), 2.64(dd, J=5.1, 2.6 Hz, 1H), 1.93-2.04 (m, 2H), 1.52 (s, 9H).

Example 9 Esterification of Alternate polyglycerol with benzotriazoleacid

A polyglycerol partially esterified with stearic acid (2.5 g, 19.8hydroxy milliequivalents; tetradecaglyceryl monostearate sold under thetrade name POLYALDO 14-1-S by Lonza, Allendale, N.J.) and benzotriazolecarboxylate 4 (8.8 g, 23.8 mmol) were transferred into a 2-neck 100 mLround bottom flask containing a magnetic stir bar. The flask was fittedwith a nitrogen inlet adapter and distillation adapter with 100 mLreceiving flask. The apparatus was placed under vacuum for one hour,then backfilled with nitrogen. The distillation head was removed, andtin (II) ethyl hexanoate (50 μL) was added to the reaction flask bysyringe under nitrogen flow. The apparatus was reassembled, then purgedunder vacuum and backfilled with nitrogen 3 times. The reaction flaskwas immersed in an oil bath that was warmed to 180° C. with constantflow of nitrogen into the 2-neck flask through the distillation adapterand out of the vacuum adapter to room atmosphere. The reaction wasstirred for three hours and then cooled to room temperature undernitrogen flow, affording the product, a UV-absorbing polyglycerol, as ayellow solid. ¹H NMR (400 MHz, CDCl₃) δ ppm 11.81 (br. s., 2H), 8.15(br. s., 2H), 7.75-8.02 (br. s, 4H), 7.34-7.58 (br. s, 4H), 7.21 (br.s., 2H), 4.93-5.32 (br, 1H), 3.17-4.50 (br. m, 38H), 2.86-3.11 (br. m,4H), 2.54-2.84 (br. m, 4H), 2.31 (br. s., 2H), 1.61 (br. s., 2H), 1.50(br. s., 18H), 1.26 (br. s., 28H), 0.89 (t, J=6.3 Hz, 3H). GPC (THF):M_(w) 1700; M_(n) 950.

Example 10 Synthesis of benzotriazole acid methyl ester

The synthesis of benzotriazole methyl ester 11 intended fortransesterification with a polymer with hydroxyl functional groups isillustrated in FORMULA XVI.Beta-[3-(2-H-benzotriazole-2-yl)-4-hydroxy-5-tert-butylphenyl]-propionicacid-poly(ethylene glycol) 300-ester (50.1 g; a UV absorbing productsold under the trade name TINUVIN 1130 by BASF Corporation, Wyandotte,Mich.) was added to a 2-neck 1 liter round bottom flask containing amagnetic stir bar. Methanol (500 mL) was added to the flask. The flaskwas immersed in an oil bath; the solution was stirred. p-TSA.H₂O (0.63g) was added to the solution. The 2-neck flask was fitted with a refluxcondenser and rubber septum; the stirred reaction mixture was brought toreflux by warming the oil bath; reflux was maintained for 17 hours. Theflask was then removed from the oil bath and allowed to cool to roomtemperature, whereupon the product precipitated as a white solid. Theprecipitate was isolated by vacuum filtration, and then recrystallizedfrom methanol; the solids were isolated by vacuum filtration and driedunder vacuum at 80° C. affording the benzotriazole methyl ester 11(18.27 g) as a white solid. ¹H NMR (400 MHz, CDCl₃) δ ppm 11.81 (s, 1H),8.16 (d, J=2.1 Hz, 1H), 7.90-7.98 (m, 2H), 7.45-7.53 (m, 2H), 7.22 (d,J=2.2 Hz, 1H), 3.71 (s, 3H), 3.01 (t, J=7.8 Hz, 2H), 2.71 (t, J=7.8 Hz,2H), 1.51 (s, 9H).

Example 11 Transesterification of benzotriazole methyl ester withpolyglycerol polymer

The transesterification of benzotriazole methyl ester 11 withpolyglycerol 3 is illustrated in FORMULA XVII. A solution ofpolyglycerol 3 solution in MeOH was concentrated by rotary evaporation;residual solvent was removed overnight under vacuum at 75° C.Polyglycerol 3 (1.36 g, 14.9 hydroxyl milliequivalents) was added to a100 mL 2-neck round bottom flask containing a magnetic stir bar.Benzotriazole methyl ester 11 (4.24 g, 12 mmol) and pTSA.H₂O (7.1 mg)was added to the flask. The flask was fitted with a nitrogen inletadapter and distillation adapter with 100 mL receiving flask. Thereaction flask was immersed in an oil bath, and the oil bath was warmedto 175° C. Within 20 minutes, all of the reactants had melted. Thereaction mixture was stirred vigorously under a stream of nitrogenovernight. The following morning, the flask was placed under vacuum;residual UV-chromophore sublimed and collected in the distillationadapter. Heating under vacuum was continued overnight. The reactionmixture was then cooled to room temperature; the UV-absorbingpolyglycerol product was obtained as a yellow, glassy solid. ¹H NMR (400MHz, CDCl₃) δ ppm 11.71 (br. s., 8H), 8.05 (br. s., 8H), 7.81 (br. s.,16H), 7.36 (br. s., 16H), 7.14 (br. s., 8H), 5.06-5.32 (br. s., 1H),3.86-4.57 (m, 16H), 3.15-3.82 (m, 30H), 2.92 (br. s., 16H), 2.68 (br.s., 16H), 1.45 (br. s., 76H), 1.24 (br. s., 28H), 0.88 (t, J=6.6 Hz,3H).

It can be seen from Examples 1-11 that analytical characterization ofthe resulting UV-absorbing polyethers was consistent with the expectedstructures. HPLC analysis of the polymers described in the examplesprovided evidence that the polymerization methods described resulted inlow concentrations of residual UV absorbing monomer.

Example 12 Summary of SPF Results

Sun protection factor (SPF) measurements for UV absorbing polymers wereperformed using the following in vitro sun protection test method.Polymer samples were measured into 8 mL glass vials. Mixed C₁₂ to C₁₅alkyl benzoates (a cosmetic oil solvent sold under the trade nameFINSOLV TN by Innospec, Newark, N.J.) was added to the vial to achievethe desired weight percent solution of polymer. A magnetic stir bar wasadded to the vial, which was then sealed with a Teflon lined screw cap.The polymer/oil solution was stirred in a 100° C. aluminum reactionblock until homogeneous. Once cooled, 32 mg of polymer solution wasapplied to a poly(methyl methacrylate) (PMMA) plate (a test substratesold under the trade name HELIOPLATE HD6 by Helioscience, Marseille,France). The solution was spread evenly over the plate using one fingerusing a latex cot until the weight of sample on the plate had decreasedto 26 mg. The baseline transmission was measured using an HD6 plate asreceived from the manufacturer. Absorbance was measured using acalibrated Labsphere UV-1000S UV transmission analyzer (Labsphere, NorthSutton, N.H., USA). The absorbance measures were used to calculate SPFindices. SPF was calculated using methods known in the art. The equationused for calculation of SPF is described by Equation 1.

SPF_(in vitro) =[∫E(λ)I(λ)dλ]/[∫E(λ)I(λ)10^(−A) ₀ ^((λ))(dλ)]  (1)

where:

E(λ)=Erythema action spectrum

I(λ)=spectral irradiance received from the UV source

A₀(λ)=mean monochromatic absorbance of the test product layer before UVexposure

dλ=Wavelength step (1 nm)

and the integrations are each performed over the wavelength range from290 nm to 400 nm.

Results of in vitro SPF testing of the polymers are reported in Examples4, 7, and 9 as [wt. % in FINSOLV TN, mean SPF value] and are also shownin Table 1.

TABLE 1 Polymer Polymer of concentrations example # (wt %) SPF STDEV 740 25 4 40 32 11 9 40 31 8

It can be seen that the UV-absorbing polyethers described were solublein oils commonly used in topical cosmetic applications. Furthermore, itwas demonstrated that solutions of polymers in these oils showedsuitable SPF values using in vitro SPF test methods.

1. A polymer composition comprising a linear ultraviolet radiationabsorbing polyether that comprises a chemically bound UV-chromophore. 2.The polymer composition of claim 1 wherein the linear ultravioletradiation absorbing polyether comprises a repeat unit selected from thegroup consisting of

where Y is the chemically bound UV-chromophore.
 3. The polymercomposition of claim 1 wherein the linear ultraviolet radiationabsorbing polyether comprises a repeat unit

where Y is the chemically bound UV-chromophore.
 4. The polymercomposition of claim 1 wherein the linear ultraviolet radiationabsorbing polyether comprises a repeat unit

where Y is the chemically bound UV-chromophore.
 5. The polymercomposition of claim 1, comprising about 50% or more of said linearultraviolet radiation absorbing polyether comprising the chemicallybound UV-chromophore.
 6. The polymer composition of claim 1, comprisingabout 90% or more of said linear ultraviolet radiation absorbingpolyether comprising the chemically bound UV-chromophore.
 7. The polymercomposition of claim 1, comprising about 95% or more of said linearultraviolet radiation absorbing polyether comprising the chemicallybound UV-chromophore.
 8. The polymer composition of claim 1, wherein thelinear ultraviolet radiation absorbing polyether comprises a backbonehaving glyceryl repeat units.
 9. The polymer composition of claim 1,wherein the linear ultraviolet radiation absorbing polyether ischaracterized as having the structure:

where R is a pendant group, Y represents the chemically boundUV-chromophore, X is a terminal group, and m and n are real numbersbetween 0 and
 1. 10. The polymer composition of claim 9, wherein m is 1and n is
 0. 11. The polymer composition of claim 9, wherein X and R areindependently selected from the group consisting of hydrogen, linearalkyl, alkenyl or alkynyl hydrocarbon chains, and linear siloxanes. 12.The polymer composition of claim 1, wherein the linear ultravioletradiation absorbing polyether is a reaction product of the ring openingpolymerization of a monomer selected from a group consisting of ethyleneoxide, propylene oxide, and a glycidyl ether.
 13. The polymercomposition of claim 12, wherein the glycidyl ether is selected from thegroup consisting of n-butyl glycidyl ether and 2-ethylhexylglycidylether.
 14. The polymer composition of claim 1, wherein theUV-chromophore is selected from the group consisting of triazoles,camphors, dibenzoylmethanes, 4-aminobenzoic acid and alkane estersthereof, anthranilic acid and alkane esters thereof, salicylic acid andalkane esters thereof, hydroxycinnamic acid and alkane esters thereof,dihydroxy-, dicarboxy-, and hydroxycarboxybenzophenones and alkane esteror acid halide derivatives thereof, dihydroxy-, dicarboxy-, andhydroxycarboxychalcones and alkane ester or acid halide derivativesthereof, dihydroxy-, dicarboxy-, and hydroxycarboxycoumarins and alkaneester or acid halide derivatives thereof, benzalmalonate, benzimidazolederivatives, benzoxazole derivatives,3-(3-(2H-benzo[d][1,2,3]triazol-2-yl)-5-(tert-butyl)-4-hydroxyphenyl),6-octyl-2-(4-(4,6-di([1,1′-biphenyl]-4-yl)-1,3,5-triazin-2-yl)-3-hydroxyphenoxy)propanoateand trioctyl 2,2′,2″-(((1,3,5-triazine-2,4,6-triyl)tris(3-hydroxybenzene-4,1-diyl))tris(oxy)) tripropanoate.
 15. Thepolymer composition of claim 1, wherein the UV-chromophore is selectedfrom the group consisting of a benzotriazole and a triazine.
 16. Thepolymer composition of claim 1 having a polydispersity index of about1.5 or less.
 17. The polymer composition of claim 1 having apolydispersity index of about 1.2 or less.
 18. The polymer compositionof claim 1 wherein said polymer composition is the reaction product of apolyglycerol ester and a UV-chromophore having a functional groupsuitable for covalent attachment to said polyglycerol ester.
 19. Acomposition comprising a cosmetically acceptable topical carrier and apolymer composition comprising a linear ultraviolet radiation absorbingpolyether that comprises a chemically bound UV-chromophore.